The present invention is directed to a system for sterilizing components such as mandrels in a packaging machine. More particularly, the present invention is directed to an automatic, continuous sterilization system for form, fill and seal packaging machines.
Form, fill and seal packaging machine are well known in the art, as are sterilization systems for use with such machines. These machines are widely used in the food packaging industry for forming a package, filling the package with a liquid or solid food (or a mixture of liquid and solid foods), and sealing the package after filling.
In such machines, sterilization systems are in place to eradicate (i.e., kill) microbes such as bacteria, yeast and mold. Commonly, the sterilization systems are directed to sterilizing the packages before and/or after forming the package, prior to filling and sealing.
Different types of sterilization systems are also used. For example, one type of sterilization system uses hydrogen peroxide as a liquid or in vapor form that is sprayed onto the exterior of the packages and/or into the interior of the packages. Other types of sterilization systems use energy in the form of, for example, ultraviolet emissions or electron beam emissions to kill these microbes. Still other types of sterilization systems use combinations of these systems and methods.
Nevertheless, prevailing sterilization systems use hydrogen peroxide that is applied directly to the packaging. The hydrogen peroxide sterilant can be applied in a sterilization station within the machine, or it can be pre-applied at a location prior to the machine proper. Exemplary arrangements for machines and machine sterilizations systems, methods and the like are disclosed in Cicha, et al., U.S. Pat. No. 6,406,666, Palaniappan, et al., U.S. Pat. No. 6,120,730, Lees, U.S. Pat. No. 6,058,678, Palaniappan, et al., U.S. Pat. No. 6,056,918 and Eno, U.S. Pat. No. 5,809,740, all of which patents are commonly assigned with the present application and are incorporated herein by reference.
Although all of these systems work well and function well, there are limits to the amount of residual hydrogen peroxide (which is generally present in the form of condensed vapor remaining on the packaging material surface) that can remain on packaging when food is introduced to the package. As such an appropriate drying time is necessary to assure that these upper limits are met.
Moreover, it is conventionally believed that microbes present in the packaging can result from contact of the packaging with portions or elements or parts of the machine. One such part, in a machine that forms, fills and seals gable-top packages or cartons, is the carton mandrel. The mandrel is that machine element around which the carton is formed (the carton is inserted onto the mandrel), for folding and sealing the carton bottom panels. Typically, the mandrels are positioned on a rotating turret and, in an indexed manner, receive cartons opened into a tubular form at a station, index the cartons to a subsequent station for pre-folding, index the cartons to another station to heat the carton panels, fold the panels into a desired pattern or orientation and “press” the heated panels on the mandrel to form the sealed cartons bottom all.
In that there are a considerable number of machine elements that contact the carton (and in particular the mandrels that contact carton interior surfaces) in this “forming” process, it is necessary to carry out sterilization following these cartons forming steps. As such, sterilization stations or tunnels are positioned on a typical machine following the forming stations.
Furthermore, it is also necessary to periodically clean, sanitize and/or sterilize the mandrels. Presently, mandrel cleaning, sanitizing or sterilizing is accomplished by stopping the package forming and filling operations and manually or automatically cleaning, sanitizing and/or sterilizing the mandrel surfaces. Ceasing the package forming and filling functions for manual or automatic cleaning of the mandrels reduces the machine efficiency and adds labor costs to overall machine operations.
In addition, manual sanitizing procedures are extremely variable due to various operator techniques and the level of operator skill and training. Manual procedures are difficult to monitor and as such make it difficult to control the consistency or efficacy of the sterilization process. Further, many manual and automatic procedures which require that production be stopped for sterilization employ sanitizers or sterilants that are liquid based and require a drying step which further reduces machine efficiency. Examples of water based products are alcohols and quats which need to dry before commencing production. If production is allowed to start prior to the machine surfaces being fully dried, the very steps that are intended to reduce contamination can contribute to further contamination and subsequent package spoilage. Additionally, these known methods are not continuous or automatic operations that can be accomplished without stopping production activities.
Furthermore, more than just meeting the sterility or cleanliness standards (which permit some amount of microbes), it is known that greater amounts of microbial contamination will result in packaged foods that have shorter shelf lives. That is, typically, as the amount of microbial contamination increases, the shelf life of the product decreases. This is of greatest concern for long or extended shelf life products and for aseptic products where the product must meet strict commercial sterility requirements. For all hygiene levels, these requirements are strictly controlled and enforced by governmental regulatory agencies such as for example the United States Food and Drug Administration (USFDA) and the United States Department of Agriculture (USDA).
It has been found that during package forming operations, mandrels are exposed to environmental factors such as dust, paper particles, plastic particles and humidity. All of these environmental factors serve to increase the microbial load on the mandrel surfaces and subsequent contamination of the interior product surfaces of the package.
It has also been observed that although microbial loading on the mandrel surfaces is generally low at the start of production, the microbial load increase over time. Thus, the contamination and spoilage microorganisms delivered to the packages will increase over time. In addition, microbial contamination in the form of condensate, water drops or other particulate forms (which are generally highly contaminated), are also readily transferred to interior product contact package surfaces.
Accordingly, there exists a need for a sterilization system for a form, fill and seal packaging machine that increases the ability to kill or otherwise eliminate microbes that may be present within the machine or on the packaging. Desirably, such a sterilization system is compatible with the overall operation of known form, fill and seal machines, and operates automatically, on a continuous basis without interruption to machine filling operations. Most desirably, such a system works in conjunction with and/or uses systems and subsystems already within the machines to provide this enhanced microbe eradication characteristic.